The present invention primarily relates to mining and subterranean well formations. More particularly, the present invention relates to an improved method and system for perforating, slotting, and cutting steel and subterranean rock; and also for fracturing a subterranean formation to stimulate the production of desired fluids therefrom.
Jetting tools are used in a number of different industries and have a variety of different applications. For instance, jetting tools are used in subterranean operations such as perforating and hydraulic fracturing.
Hydraulic fracturing is often utilized to stimulate the production of hydrocarbons from subterranean formations penetrated by well bores. Typically, in performing hydraulic fracturing treatments, the well casing, where present, such as in vertical sections of wells adjacent the formation to be treated, is perforated. This perforating operation can be performed using explosive means or hydrajetting. Where only one portion of a formation is to be fractured as a separate stage, it is then isolated from the other perforated portions of the formation using conventional packers or the like, and a fracturing fluid is pumped into the well bore through the perforations in the well casing and into the isolated portion of the formation to be stimulated at a rate and pressure such that fractures are formed and extended in the formation. A propping agent may be suspended in the fracturing fluid which is deposited in the fractures. The propping agent functions to prevent the fractures from closing, thereby providing conductive channels in the formation through which produced fluids can readily flow to the well bore. In certain formations, this process is repeated in order to thoroughly populate multiple formation zones or the entire formation with fractures.
One method for fracturing formations may be found in U.S. Pat. No. 5,765,642, incorporated herein by reference in its entirety, whereby a hydrajetting tool is utilized to jet fluid through a nozzle against a subterranean formation at a pressure sufficient to form a cavity and fracture the formation using stagnation pressure in the cavity.
Hydrajetting in oil field applications often involves long duration jetting for cutting a multitude of casing strings and perforations. This problem is greatly magnified when a hydrajetting tool is utilized to form a cavity and fracture the formation using the stagnation pressure in the cavity as discussed in U.S. Pat. No. 5,765,642. This is because millions of pounds of proppants may be flowing through the hydrajetting tool at very high velocities in order to form a cavity and fracture the formation. One solution for withstanding the abrasive forces encountered during the jetting process is to make the jetting tool from an ultra-hard material. However, the jetting tool cannot be made of a very hard material to avoid erosion because such materials are brittle and will shatter during jetting operations or when the jetting tool is moved in and out of the jetting location. Consequently, the current jetting tools comprise a cylindrical structure which cannot withstand the abrasive forces. In some applications a fluid jet that is made of a hard material is installed on the cylindrical structure. Hence, one disadvantage of the current hydrajetting methods is that the jetting tool is eroded during operation. In order to deal with this erosion the jetting tool must be extracted from the hole to be repaired or replaced. The extraction of the jetting tool can be expensive and could also lead to a job failure. In such situations it would be desirable to have a method and tool for delivering fluids to the formation to be fractured which could withstand the impact of the erosive forces.